Plug



FIG. 1 is a perspective view illustrating a plug according to an embodiment of our design;

FIG. 2 is a front view thereof; the rear view being a mirror image;

FIG. 3 is a right side view thereof; the left side view being a mirror image;

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof. 

The ornamental design for a plug, as shown and described. 